import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

/**
 * 项目名称：wangxu
 * 类 名 称：HJ34
 * 描 述：
 * 创建时间：2023/3/1 11:40 上午
 * 创 建 人：wang-xu
 */
public class HJ34 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNext()) {
            String str = in.next();
            List<Character> list = new ArrayList<>();
            for (int i = 0; i <str.toCharArray().length; i++) {
                list.add(str.toCharArray()[i]);
            }
            Collections.sort(list);
            StringBuilder sb = new StringBuilder();
            for (char c:list) {
                sb.append(c);
            }
            System.out.println(sb.toString());
        }
    }
}
